RMD-13-04: Consolidated Pest Risk Management Document for pest plants regulated by Canada
Appendix 9B: Risk Management Considerations for Nassella trichotoma (serrated tussock)

• Values at Risk
• Potential Mitigation Measures for Natural Means of Dispersal
• Potential Mitigation Measures for Intentional Introduction Pathways
• Potential Mitigation Measures for Non-intentional Introduction Pathways

Values at Risk

Seed Industry

In 2007, 162,200 tons of Canadian seed were exported to the U.S., for an approximate value of $197.6 million. If Nassella trichotoma becomes established in Canada, it could complicate seed trade between the U.S. and Canada (Statistics Canada in Agriculture Canada 2008). On several occasions forage grass seed lots of South American origin have been found to be contaminated with seeds of this weed. This has caused problems for the Canadian seed trade when seed lots containing serrated tussock seeds were re-exported to the U.S. It was largely to address these trade concerns that the species was added to the Weed Seed Order as a prohibited noxious weed seed in July 2005.

The potential range of Nassella trichotoma in Canada is limited to the West Coast of British Columbia, where there is almost no forage seed production (Statistics Canada 2007). Its direct impact on seed trade is thus relatively low and is limited to re-exportation to the U.S (Table 2).

Garry Oak Ecosystem

The Garry oak ecosystem is rare and irreplaceable because of its historical and ecological significance. This landscape contributes both to the sense of place and regional identity of the inhabitants of Vancouver Island.

The British Columbia Ministry of Environment, Lands and Parks has two Ecological Reserves that primarily focus on Garry oak ecosystems. The Garry Oak Meadow Preservation Society, the British Columbia Conservation Data Centre and the Canadian Forest Service have initiated programs to promote the preservation of Garry oak ecosystems in Canada.

Source: Statistics Canada in Industry Canada 2009.

Cost of control

If Nassella trichotoma becomes established in natural ecosystems, including the Garry oak ecosystem of BC, it could be arduous and costly to eradicate.

The most effective control method in New Zealand, chipping combined with herbicide application, is expensive both in labour costs and cost of chemicals. Control costs vary with the degree of infestation and land use (arable versus non-arable) (Vere and Campbell 1984). Costs for control on moderately to heavily-infested land were estimated at $98.50 to $107.35^{Footnote 1} per hectare (Vere and Campbell 1984). The same authors explain that continued treatment of heavily-infested land must be continued for up to 22 years before an economic benefit can be expected.

Glyphosate seems to be the only pesticide that is currently registered in Canada that has been successful in controlling Nassella trichotoma. Glyphosate, a non-selective herbicide, kills a broad spectrum of plants. Its use would affect native species within the treated area, including endangered species (Allison 2006).

Potential Mitigation Measures for Natural Means of Dispersal

No measures are required. Nassella trichotoma is not present along the Canadian border. It is not likely to enter Canada by natural means.

Potential Mitigation Measures for Intentional Introduction Pathways

Plants for Planting excluding Seed

Previous imports

The CFIA considers Nassella trichotoma as not cultivated in Canada.

• Based on available information, no plant in the Nassella genus has been recently imported into Canada (CFIA internal data).
• There are anecdotal records of Nassella trichotoma being sold in Vancouver, British Columbia (UBC Botanical Garden 2006, UBC Botanical Garden 2008). This plant is not otherwise available in the Canadian market (CNLA 2009b).

Potential risk mitigation measures

Non-regulatory measures

• 1. Use sterile cultivars if they exist.
• 2. Encourage voluntary cessation of the sale of Nassella trichotoma. Voluntary cessation is not effective by itself, but could support other measures.
• 3. Increase public awareness of the risk posed by this plant, publish a factsheet online, and distribute awareness material to garden centers, botanical gardens, gardener associations, horticulture industry groups, etc. This measure is not effective by itself, but could support other measures.

Regulatory measures

• 4. Allow sale of Nassella trichotoma with special conditions such as not to be grown close to natural areas and mandatory control of adventives. This is not considered effective because once the plant is grown in private gardens; CFIA does not have adequate resources for monitoring populations.
• 5. Regulate Nassella trichotoma under the Plant Protection Act as a quarantine pest:
  • Refuse to issue Permits to Import for plants of Nassella trichotoma^{Footnote 2};
  • Will require that importers of material from regions other than the continental U.S. specify the scientific name of any species of Nassella when applying for a Permit to Import plants and propagative material;
  • Require that the scientific name of any Nassella species be provided on the Phytosanitary Certificate for all plants exported to Canada from the continental U.S. However, imports from the U.S. are very unlikely to occur because: (1) Nassella trichotoma is a Federal Noxious Weed in the U.S. and its cultivationand movement is prohibited; and (2) Nassella trichotoma is not commonly sold as an ornamental plant.

Trade implications

• The loss of market is expected to be very low because (1) Nassella trichotoma is a Federal Noxious Weed in U.S. and most imports of plants for planting to Canada originate in the U.S.; and (2) Nassella trichotoma is not a popular ornamental plant and alternative ornamental grasses are readily available.
• Foreign exporters would need to obtain phytosanitary certificates for any Nassella species. National Plant Protection Organizations of the exporting country should be able to distinguish Nassella species.

Cost-effectiveness and Feasibility

• No additional resources would be required at the CFIA Plant Health and Biosecurity Permit Office. Applications for a Permit to Import are reviewed by officers on a regular basis.
• An important increase in demand for plant and seed identification is not expected on the CFIA laboratory. Plants and seeds of Nassella trichotoma are readily identifiable.

Seed of Nassella trichotoma

Previous imports

Unknown. No figures are available specifically for Nassella trichotoma.

Potential risk mitigation measures

• 1. Maintain regulation of Nassella trichotoma as a Class 1, prohibited noxious weed, under the Weed Seeds Order of the Seeds Act^{Footnote 3}.
  • This species meets the definitions for Class 1^{Footnote 4} species under the Weed Seeds Order.
  • The importation and sale of Class 1 seeds are prohibited in Canada. Imported seed lots require a certificate of analysis stating Nassella trichotoma is absent from the seed lot before it can be imported.
• 2. Regulate as a quarantine pest under the Plant Protection Act and add this species to the List of Pests Regulated by Canada (CFIA 2009) in order to:
  • Prevent the importation, movement, and cultivation of this species in Canada. Currently, seed of many new crop species, such as field crops, can be imported without a Permit to Import or a Phytosanitary Certificate from throughout the world.
  • Enable inspectors to take appropriate action for the purposes of eradicating the pest or preventing its spread^{Footnote 5}.
• 3. Regulatory actions under the Plant Protection Act could include the following:
  • Prohibit importation of Nassella trichotoma seed and refuse to issue Permits to Import for seed of Nassella trichotoma^{Footnote 6}. Require importers of plant material from the non-continental U.S. to apply for a Permit to Import with scientific name specified.
  • Seed of horticultural plants is not within the scope of CFIA's draft directive D-08-04 on plants for planting (CFIA 2008). Therefore phytosanitary requirements will be specified under a new regulatory policy directive or D-08-04 will be revised.

Trade implications

The loss of market is expected to be very low (see Section V, c. Trade Implications).

Cost-effectiveness and Feasibility

The CFIA Seed Program is already in place to prevent the entry of prohibited noxious weeds. Verification of compliance is carried out through the Seed Marketplace Monitoring Program^{Footnote 7}.

Potential Mitigation Measures for Non-intentional Introduction Pathways

Seed of Forage Grasses

Previous imports

• The total value of forage grass seed^{Footnote 8} imported in 2008 was around $26 million (Industry Canada 2009).
• The total value of forage grass seeds imported in 2008 from countries where Nassella trichotoma is present was 12% of total imports, for a value of $3.1 million (see Figure 3 and Appendix 9C).

Potential risk mitigation measures

1. Maintain the regulation of Nassella trichotoma as a prohibited noxious weed (Class 1) under the Weed Seeds Order of the Seeds Act.
   • This species meets the definitions for Class 1 species under the Weed Seeds Order.
   • All imported and domestic seed lots must be free of prohibited noxious weed seeds. Imported seed lots would require a certificate of analysis stating Nassella trichotoma is absent from the seed lot before it can be imported.
2. Regulate Nassella trichotoma as a quarantine pest under the Plant Protection Act and add this species to the List of Pests Regulated by Canada (CFIA 2009).
   • This could prevent the importation, movement, and cultivation of this species in Canada.
   • Exporters could be required to obtain a phytosanitary certificate stating freedom from Nassella trichotoma^{Footnote 9}.
   • Phytosanitary agreements could be negotiated to certify imports from pest free areas and/or recognize noxious weed certification in countries or states of origin.

Description of Figure 3

This figure depicts the imports of forage seed into Canada from countries where serrated tussock is present from 1999 to 2008. These include Chile, Uruguay Argentina, New Zealand, Australia, Italy, Brazil and South Africa. In 1999, Canada received the most imports from Argentina (approximately $2,400,00 CAN worth) and in 2008 Canada received the most imports from Chile (approximately $1,250,000 CAN worth).

Trade implications

• This measure facilitates seed trade with the U.S. where Nassella trichotoma is listed as a Federal Noxious Weed. It is also listed as a noxious weed in 24 states.
• NPPOs of exporting countries and seed regulatory agencies will need to devote resources towards inspection of seed lots and issuance of phytosanitary certificates. Laboratories in exporting countries will need to be able to identify seeds of Nassella trichotoma within a seed sample. NPPOs of exporting countries and seed regulatory agencies need to ensure freedom of Nassella trichotoma in seed lots, otherwise CFIA can refuse import.

Cost-effectiveness and Feasibility

• Regulation of Nassella trichotoma as a Class 1 prohibited noxious weed is already in place (see Section V, c. Trade Implications).
• The seeds of Nassella trichotoma are easily identified.

Hay and Straw

Previous imports

• The total value of hay and straw imports was around $13 million in 2008; 98% of this value came from the U.S. (Industry Canada 2009).
• Between 1999 and 2004, limited quantities (less than 0.2%) of hay and straw were imported from Spain, where Nassella trichotoma is present. Since 2004, hay and straw has not been imported from countries where Nassella trichotoma is present (Industry Canada 2009).

Potential risk mitigation measures

No measures required. The level of risk associated with imports of hay and straw into Canada is relatively low because (1) they originate primarily from areas where Nassella trichotoma is not present, and (2) Nassella trichotoma rarely occurs in cultivated crops,such as cultivated grassland.

Live Animals

Previous imports

Between 1999 and 2008, no significant numbers of live sheep or goats for reproduction have been imported into Canada from countries where Nassella trichotoma is present (CFIA internal data).

Potential risk mitigation measures

No measures are required.

Raw Wool

Previous imports

The total value of raw wool imports was around $3.1 million in 2008; 70% of this value came from Australia, New Zealand and Argentina, where Nassella trichotoma is present (Industry Canada 2009).

Potential risk mitigation measures

No measures are required.

• The vegetative matter is removed from commercial wool by carbonization^{Footnote 10}.
• Raw wool and raw hides imported into Canada from all countries require CFIA inspection. They must be free from feces, blood, ectoparasites and dirt (plant and plant parts are considered to be dirt) or it will be refused entry (Health of Animals Act, Directive AHPD-DSAE-2001-1-1 (CFIA 1990)).

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